Castro has been a central figure in San Antonio politics for nearly as long as the San Antonio Spurs have been really good at basketball. He was elected to the City Council in 2001 at age 26, making him the youngest Council member in the city's history. After two consecutive two-year terms, he narrowly lost a bid for mayor in 2005. He won the mayor's seat in 2009, then won re-election twice by wide margins, gaining 82.9 percent of the vote in 2011 and 67 percent of the vote in 2013 (a contest in which he did not face a serious challenger).

Using Castro's accomplishments as mayor as a lens to measure his potential as a cabinet member is tricky.

But using Castro's accomplishments as mayor as a lens to measure his potential as a cabinet member is tricky. San Antonio's city government is a council-manager system. Unlike the strong-mayor governments of Chicago or New York, San Antonio's government is led by a city manager, which is appointed by the City Council. The city charter invests in the city manager the authority to "execute the laws and administer the government of the city."

Serving in the comparatively ceremonial role of mayor, Castro largely inherited the major urban accomplishment of his administration: the Museum Reach expansion of the San Antonio Riverwalk, which was completed the same month Castro was elected. This is an achievement in which San Antonio's mayor did play a major role. Mayor Phil Hardberger, who beat Castro for office in 2005 and was re-elected for a second term in 2007, has received credit for pushing the City Council to finally adopt the long-planned expansion. Hardberger left office with an 86 percent approval rating.

The 1.3-mile expansion, which doubled the length of the existing Riverwalk, connected the existing River Bend area downtown with the San Antonio Museum of Art and the redeveloped former Pearl Brewery. The expansion continued with the Mission Reach segment under Castro. While NBA hall-of-famer Charles Barkley calls the San Antonio River a "dirty creek," there's no doubt that the Riverwalk has transformed the city's downtown economically and environmentally, drawing 11.5 million visitors and generating $3.1 billion annually.

By and large, Castro's accomplishments have to be measured by his work elsewhere. Perhaps most notably, he was a part of the Council that successfully lured Toyota and several suppliers to build a pickup-truck factory 10 miles south of downtown in 2003. Up until the recession, San Antonio enjoyed a jobs boom: Texas Monthlyreported in 2007 that 97 companies opened operations in San Antonio between 2003 and 2007, creating more than 22,000 jobs. He also worked to curb sprawl, defeating a PGA-approved golf course and a vast suburban development outside the city.

San Antonio's population declined somewhat once the recession arrived, but the city suffered a smaller rate of population loss than Houston. By now, it has rebounded, with a population growth rate that rivals that of Austin.

Last week, the Texas Workforce Commission reported the highest monthly job growth for Texas in three years. San Antonio has seen its share of that growth; the city's unemployment rate is well below that of the national average (though not quite so low as in boomtown Austin). Analysts expect the positive trend to continue this year. Keith Phillips, senior economic policy adviser for the Federal Reserve Bank of Dallas, predicted in January that San Antonio would add 22,400 jobs in 2014, expanding the job base by 2.5 percent.

It's hard to attribute a downward unemployment trend in San Antonio that's consistent with the broader trend seen in big Texas cities and in the United States to something magical in the San Antonio River's water. It's even harder to attribute the city's successes to Castro specifically.

Castro's weak mayoralty might play in his favor as his record comes under closer scrutiny, though. For example, HUD blasted San Antonio in 2012 for misspending some $8.6 million in federal funds dedicated for purchasing, renovating, and reselling blighted residences.

There's a lot to love about San Antonio. It's a sprawl-oriented city that's building out a successful bike-share program. To the extent that there is a Texas Miracle, San Antonio hasn't missed out on it. By all accounts, the city is on its way tomeeting its SA2020 goals for sustainable growth. But the city's strengths (and weaknesses) have relatively less to do with the mayor compared to other major U.S. cities.